JSON Lines Validator
Validate newline-delimited JSON records and locate malformed lines without uploading logs.
How to use this utility
JSON Lines (JSONL/NDJSON) stores one independent JSON value per line, making it useful for event logs and data export. This checker parses lines independently and reports valid records, invalid line numbers, blank lines, and value types. It permits objects, arrays and primitive JSON values, but it does not validate a custom event schema. At most ten invalid line numbers are shown, and processing is limited to 5,000 lines and 100,000 characters per run. Nothing is uploaded.
Local processing: This page performs calculations in your browser. It does not make remote API requests, persist your input, or send telemetry. Input is capped to protect responsiveness.
Format a JSON document